Antenna and filter structures

Abstract

A combined filter and antenna structure comprising a multi-mode cavity filter and an antenna, wherein: the filter comprises: a dielectric body provided with a conductive covering; and an interface arranged to exchange energy between a standing wave in the body and a current conveyed external to the body; and the antenna is arranged to exchange energy between a travelling wave outside the body and a standing wave inside the body and the antenna comprises: a first window provided in the covering.

1 . A combined filter and antenna structure comprising a multi-mode cavity filter and an antenna, wherein:
 the filter comprises:
 a dielectric body provided with a conductive covering; and 
 an interface arranged to exchange energy between a standing wave in the body 
 and a current conveyed external to the body; and 
   the antenna is arranged to exchange energy between a travelling wave outside the body and a standing wave inside the body and the antenna comprises:
 a first window provided in the covering. 
   
     
     
         2 . The structure of  claim 1 , wherein the interface comprises a second window provided in the covering and a contact of conductive material connected to the body in the second window. 
     
     
         3 . The structure of  claim 2 , wherein the contact is a patch of conductive material provided on the body in the second window. 
     
     
         4 . The structure of  claim 3 , wherein the patch extends to an edge of the second window and is electrically connected to the covering. 
     
     
         5 . The structure of  claim 2 , wherein the contact is a conductive probe penetrating into the body in the second window. 
     
     
         6 . The structure of  claim 1 , wherein the first window is a straight slot in the covering. 
     
     
         7 . The structure of  claim 6 , wherein the slot is parallel or perpendicular to a current flow that corresponds to a standing wave that will be established in the body when the structure is in use. 
     
     
         8 . The structure of  claim 1 , wherein the first window is cruciform in the manner of first and second intersecting straight slots. 
     
     
         9 . The structure of  claim 8 , wherein the first slot runs perpendicular to the second slot. 
     
     
         10 . The structure of  claim 8 , wherein the first and second slots are parallel with, respectively a first standing wave and a second standing wave that will be established in the body when the structure is in use. 
     
     
         11 . The structure of  claim 1 , wherein the interface comprises a second window provided in the covering and a contact of conductive material connected to the body in the second window. 
     
     
         12 . The structure of  claim 10 , wherein the interface comprises a second window provided in the covering, a first conductive track on the body in the second window and a second conductive track on the body in the second window and the first and second tracks are configured to preferentially couple to the first and second standing waves, respectively. 
     
     
         13 . The structure of  claim 1 , wherein the antenna further comprises an island of conductive material on the body in the first window. 
     
     
         14 . The structure of  claim 13 , wherein the interface comprises a second window provided in the covering and a contact of conductive material connected to the body in the second window and the antenna further comprises a ground plane separated from the island and the ground plane is positioned to at least partially cover the second window. 
     
     
         15 . The structure of  claim 1 , wherein the covering is a coating on the body. 
     
     
         16 . The structure of  claim 2 , wherein the first and second windows are parallel with one another. 
     
     
         17 . A duplexer comprising two combined filter and antenna structures, wherein each combined filter and antenna structure comprises:
 a multi-mode cavity filter and an antenna, wherein:
 the filter comprises: 
 a dielectric body provided with a conductive covering; and 
 an interface arranged to exchange energy between a standing wave in 
 the body and a current conveyed external to the body; and 
   the antenna is arranged to exchange energy between a travelling wave outside the body and a standing wave inside the body and the antenna comprises:
 a first window provided in the covering.